WO2018169678A1

WO2018169678A1 - Roller retraction apparatus and method in a glass drawing process

Info

Publication number: WO2018169678A1
Application number: PCT/US2018/019897
Authority: WO
Inventors: Kenji Akiyoshi; Takahiro Yamada
Original assignee: Corning Incorporated
Priority date: 2017-03-13
Filing date: 2018-02-27
Publication date: 2018-09-20
Also published as: TW201838939A

Abstract

An apparatus for drawing a glass ribbon including a roller assembly, a biasing assembly, and a retraction assembly. The roller assembly includes a roller. The biasing assembly is configured to selectively move the roller relative to the glass ribbon. The retraction assembly is transitionable between a first state and a second state. In the first state, the retraction assembly is free of mechanical coupling to the biasing assembly. In the second state, the retraction assembly is mechanically coupled to the biasing assembly. A location of the roller relative to the glass ribbon is unaffected by the retraction assembly in the first state. In the second state, operation of the retraction assembly causes the roller assembly to retract away from the glass ribbon.

Description

ROLLER RETRACTION APPARATUS AND METHOD IN A GLASS DRAWING

PROCESS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of prior of U.S. Provisional Application Serial No. 62/470,555 filed on March 13, 2017 the contents of which are relied upon and incorporated herein by reference in their entirety as if fully set forth below..

BACKGROUND

Field

[0002] The present disclosure generally relates to apparatuses and methods for making glass. More particularly, it relates to retraction of one or more roller assemblies utilized in a glass drawing apparatus.

Technical Background

[0003] One method of forming a thin sheet of glass is by a drawing process where a ribbon of glass is drawn from a reservoir of molten glass. With a down-draw process (e.g., fusion draw process), the ribbon is drawn downward, typically from a forming body. Once the ribbon is formed, individual sheets of glass can be cut from the ribbon. Fusion draw processes are used in glass manufacturing operations to produce thin glass sheets that are used in a variety of products including flat panel displays. Glass sheets produced according to these processes typically exhibit enhanced flatness and smoothness compared to glass produced by different methods, such as the float method.

[0004] In a conventional down-draw process, such as a fusion down-draw process, the molten glass is formed into the glass ribbon contained within a draw chamber defined by a shroud that surrounds the ribbon. Among other things, the shroud serves to maintain a consistent thermal environment in the region defined by the shroud and surrounding the glass ribbon. Roller pairs contact or pinch opposite sides of the glass ribbon, for example at edges of the ribbon. The rollers (or rolls) may be used to apply a pulling force to the glass ribbon, to apply a transverse tension to the glass ribbon, or merely to guide the glass ribbon. Accordingly, a rotational force may be applied to one or more of the rollers, or one or more of the rollers may be freewheeling and the rotational force applied to the rollers by the descending glass ribbon. Oftentimes, a series of roller assembly pairs are provided in the down-draw direction.

[0005] Production roller assemblies or mechanisms typically allow the roller to move horizontally and/or vertically from the glass contact area. This accommodates geometric tolerances of the rollers, run out and tolerance changes in operations. Further, production roller mechanisms typically allow the roller to move far away from the glass for maintenance access, process restart, and other practical considerations. Also, the rollers can accommodate thickness changes at the edges of the glass ribbon, or dimensional variations in the rollers themselves. In this regard, efforts have been made to monitor a pinch force generated by a particular roller pair and automatically make fine adjustments in the position or level of contact of a particular roller relative to the glass ribbon.

[0006] While actively effecting slight changes in the position of a roller operating to pull or guide a glass ribbon is beneficial, in other instances, a more immediate and gross movement of the roller is desired. For example, with the down-draw process, a defect (e.g., crack) in the glass ribbon can sometimes occur downstream of the rollers. In some instances, the defect then propagates through the glass ribbon in the upstream direction, and can result in glass ribbon breakage at or near a roller. The broken glass, in turn, can damage the rollers. Possible roller damage under these circumstances can be minimized or avoided if one of the rollers of the roller pair at or near the glass ribbon break were retracted from contact with the glass ribbon surface immediately upon recognizing a potential concern. While production roller designs may afford an operator the ability to manually move a roller, it can be difficult at best for an operator to access the glass manufacturing apparatus or machine and manually move the roller in a timely fashion. Moreover, the elevated heat associate with the glass drawing process can give rise to possible operator harm, and presents a harsh environment that is not conducive to consistent operation of an automated device (e.g., an actuator). [0007] Accordingly, alternative apparatuses and methods for retracting a roller used in a glass drawing process are disclosed herein.

SUMMARY

[0008] Some embodiments of the present disclosure relate to an apparatus for drawing a glass ribbon. The apparatus includes a roller assembly, a biasing assembly, and a retraction assembly. The roller assembly comprises a roller. The biasing assembly is configured to selectively change a location of the roller relative to the glass ribbon. The retraction assembly is transitionable between a first state and a second state. In the first state, the retraction assembly is free of mechanical coupling to the biasing assembly. In the second state, the retraction assembly is mechanically coupled to the biasing assembly. With this construction, a location of the roller assembly relative to the glass ribbon is unaffected by the retraction assembly in the first state. Upon transitioning of the retraction assembly to the second state, a force generated by the retraction assembly can be applied to the biasing assembly, causing the roller to retract away from the glass ribbon. In some embodiments, the retraction assembly comprises a drive unit and a line connected to and extending therefrom. In some embodiments, the biasing assembly comprises a stage coupled to the roller and a linkage connected to the stage. In yet other embodiments, the biasing assembly further comprises an arm projecting from the linkage and a capture element coupled to the arm. In related embodiments, the retraction assembly further comprises an engagement element attached to the line opposite the drive unit. With these optional embodiments, the engagement element can be spaced apart from and below the capture element in the first state of the retraction assembly; the engagement element can subsequently be lifted into contact with the capture element with operation of the drive unit to establish a mechanical coupling. In some embodiments, the drive unit includes an actuator that rotatably drives a hub or rotor to which the line is secured. With these and related embodiments, the actuator can be installed at a location distant from high temperature regions of the draw apparatus. [0009] Yet other embodiments of the present disclosure relate to a glass manufacturing apparatus comprising a draw apparatus configured to draw a glass ribbon from a forming apparatus along a draw path extending transverse to the width of the glass ribbon. The draw apparatus comprises a roller assembly, a biasing assembly and a retraction assembly. The roller assembly comprises a roller. The biasing assembly is configured to selectively change a location of the roller relative to the glass ribbon. The retraction assembly is transitionable between a first state and a second state. In the first state, the retraction assembly is free of mechanical coupling to the biasing assembly. Further, the roller contacts the glass ribbon. In the second state, the retraction assembly is mechanically coupled to the biasing assembly. In some embodiments, the glass manufacturing apparatus further comprises a shroud defining a chamber within which the glass ribbon travels; with these and related embodiments, a drive unit of the retraction assembly is maintained outside of the shroud.

[0010] Yet other embodiments of the present disclosure relate to a method for controlling a glass manufacturing apparatus. The method includes drawing a glass ribbon through a draw apparatus. The draw apparatus comprises a roller assembly, a biasing assembly, and a retraction assembly. The roller assembly is positioned adjacent an edge portion of the glass ribbon. The biasing assembly is coupled to the roller assembly. The retraction assembly is free of mechanical coupling to the biasing assembly, and the step of drawing comprises engaging the glass ribbon with the roller assembly. The glass ribbon is monitored for defects downstream of the roller assembly. The retraction assembly is actuated upon detection of a defect to mechanically couple the retraction assembly to the biasing assembly. A force is transferred from the retraction assembly to the roller assembly after the mechanical coupling, thereby disengaging the roller assembly from the glass ribbon. With some methods of the present disclosure, roller assembly retraction can be accomplished by an operator immediately after a glass ribbon defect (e.g., crack) is discovered, minimizing possible damage to the roller assembly.

[0011] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0012] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 schematically depicts a glass manufacturing apparatus in accordance with principles of the present disclosure, with portions shown in block form;

[0014] FIG. 2 is a simplified edge view of a portion of a draw apparatus of the glass manufacturing apparatus of FIG. 1 drawing a glass ribbon from a forming apparatus, with portions shown in block form;

[0015] FIG. 3 is an enlarged perspective view of a portion of the draw apparatus of FIG. 2, including a retraction assembly in accordance with principles of the present disclosure in a first state;

[0016] FIG. 4 is a perspective view of a biasing assembly and roller assembly of the draw apparatus of FIG. 2 and illustrating transitioning from a production state to a retracted state;

[0017] FIG. 5 is a perspective view of the draw apparatus of FIG. 2, including the retraction assembly in a second state;

[0018] FIG. 6 is a perspective view of the draw apparatus of FIG. 2 and illustrating operation of the retraction assembly to retract the roller assembly; [0019] FIG. 7 A schematically illustrates portions of the biasing assembly and the retraction assembly of FIG. 3 under normal glass drawing conditions;

[0020] FIG. 7B is an enlarged to view of a capture element useful with the biasing assembly of FIG. 7 A; and

[0021] FIG. 8 is a perspective view of portions of another draw apparatus useful with the glass manufacturing apparatus of FIG. 1, including an alternative retraction assembly in accordance with principles of the present disclosure.

DETAILED DESCRIPTION

[0022] Reference will now be made in detail to various embodiments of apparatuses and methods for roller retraction assemblies and draw apparatus used in glass ribbon and glass manufacturing operations. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. FIG. 1 generally depicts a glass manufacturing apparatus used in the production of glass in a draw operation. The glass manufacturing apparatus processes batch materials into molten glass, which is then introduced to a forming apparatus from which the molten glass flows to form a glass ribbon. The glass ribbon is contacted by one or more roller pairs positioned proximate to the glass ribbon. The roller pair(s) contact the glass ribbon and apply force to the glass ribbon to control parameters, such as the linear speed and thickness, of the subsequently solidified glass ribbon.

[0023] Draw apparatuses according to the present disclosure incorporate a retraction assembly operable to retract at least one roller assembly of the roller pair. The at least one roller assembly can be connected to a biasing assembly of a conventional design. The retraction assembly can comprise a drive unit, and is configured and arranged such that the retraction assembly is free of mechanical coupling to the biasing assembly, and thus to the at least one roller, under normal operation of the draw apparatus. Thus, some retraction assemblies of the present disclosure do not negatively affect normal or expected draw apparatus operation. When prompted by an operator, the drive unit operates to establish a mechanical coupling to the biasing assembly, for example via a line of the retraction assembly, and further operates to effect retraction or displacement of the roller assembly. The roller assembly can be caused to move away from the other roller assembly of the roller pair and/or from the glass ribbon. The drive unit can comprise an actuator, with the retraction assembly configured and arranged such that the actuator is installed away from a region of the roller pair, and thus away from highly elevated temperatures of the glass drawing operation. The actuator enables remote actuation to enable a rapid response to process concerns, such as defects or cracks in the glass ribbon downstream of the roller pair.

[0024] Referring now to FIG. 1, a glass manufacturing apparatus 100 that incorporates a fusion process to produce a glass ribbon is depicted. The glass manufacturing apparatus 100 includes a melting vessel 110, a fining vessel 115, a mixing vessel 120, a delivery vessel 125, a forming apparatus 135, a draw apparatus 200, and a cutting apparatus 150. The glass manufacturing apparatus 100 produces a continuous glass ribbon 105 from batch materials, by melting and combining the batch materials into molten glass, distributing the molten glass into a preliminary shape, applying tension to the glass ribbon 105 to control dimensions of the glass ribbon 105 as the glass cools and viscosity increases, and cutting discrete glass sheets 155 from the glass ribbon 105 after the glass has gone through a visco-elastic transition and has mechanical properties that give the glass sheets 155 stable dimensional characteristics. The visco-elastic region of the glass ribbon 105 extends from approximately the softening point of the glass to the strain point of the glass. Below the strain point, the glass is considered to behave elastically.

[0025] In operation, batch materials for forming glass are introduced into the melting vessel 110 as indicated by arrow 112 and are melted to form molten glass 126. The molten glass 126 flows into the fining vessel 115, which is maintained at a temperature above that of the melting vessel 110. From the fining vessel 115, the molten glass 126 flows into a mixing vessel 120, where the molten glass 126 undergoes a mixing process to homogenize the molten glass 126. The molten glass 126 flows from the mixing vessel 120 to the delivery vessel 125, which delivers the molten glass 126 through a downcomer 130 to an inlet 132 and into the forming apparatus 135.

[0026] The forming apparatus 135 depicted in FIG. 1 is used in a fusion draw process to produce glass ribbon 105 that has high surface quality and low variation in thickness. The forming apparatus 135 includes an opening 136 that receives the molten glass 126. The molten glass 126 flows into a trough 137 and then overflows and runs down the sides of the trough 137 in two partial ribbon portions before fusing together below a bottom edge 139 (root) of the forming apparatus 135. The two partial ribbon portions of the still-molten glass 126 rejoin with one another (e.g., fuse) at locations below the root 139 of the forming apparatus 135, thereby forming the glass ribbon 105. The glass ribbon 105 is drawn downward from the forming apparatus 135 by the draw apparatus 200. While the forming apparatus 135 as shown and described herein implements a fusion draw process, it should be understood that other forming apparatuses may be used including, without limitation, slot draw apparatuses and the like.

[0027] The draw apparatus 200 includes one or more roller assemblies 210, one or more biasing assemblies 212, and one or more retraction assemblies 214. In the non-limiting embodiment of FIG. 1, the biasing assembly 212 and retraction assembly 214 are illustrated as being associated with a first roller assembly 210a for ease of explanation. While the first roller assembly 210a of FIG. 1 is an upstream-most one of the roller assemblies 210 (i.e., closest to the root 139), in other embodiments, a retraction assembly need not be provided for the upstream-most roller assemblies 210. A shroud 216 surrounds the upper reaches of the glass ribbon 105 below the root 139 and connects with an upper enclosure 218 that houses the forming apparatus 135. The roller assemblies 210 are arranged at positions along the draw apparatus 200 to contact the glass ribbon 105 as the glass ribbon 105 moves through the draw apparatus 200. Each of the roller assemblies 210 includes a roller optionally comprising a shaft 220 and a contact surface 222 disposed over the shaft 220. The contact surface 222 can assume various forms appropriate for contacting the glass ribbon 105. As understood by one of skill in the art, support structures, bearings, and a means for a driving force (e.g., a drive motor), if needed, can also be provided that support and/or act upon the shaft 220. That is to say, one or more of the roller assemblies 210 can be driven, whereas other of the roller assemblies 210 can be freewheeling (e.g., non- driven idler rollers). In the embodiment depicted in FIG. 1, each of the roller assemblies 210 extends across only a portion of the width of the glass ribbon 105, and each is positioned proximate to an edge of the glass ribbon 105. In other embodiments (not shown), one or more of the roller assemblies 210 extend across the entire width of the glass ribbon 105. Regardless, one or more of the roller assemblies 210 can serve to draw the glass ribbon 105 along a draw path extending transverse to the width of the glass ribbon 105.

[0028] With additional reference to FIG. 2, two of the roller assemblies 210 can be arranged opposite one another to define a roller pair 230. The first and second roller assemblies 210 of the roller pairs 230 identified in FIG. 2 are positioned to contact opposite sides of the glass ribbon 105. As reflected generally by FIG. 2, one or more (including all) of the roller assemblies 210 are connected to a corresponding one of the biasing assemblies 212 (represented in block form). For ease of understanding, FIG. 2 depicts one biasing assembly 212 connected to the first roller assembly 210a. Non-limiting examples of the biasing assembly 212 are described in greater detail below. The biasing assembly 212 is generally configured to apply a bias force onto the corresponding roller assembly 210 appropriate to pinch the glass ribbon 105 between the roller assemblies 210 of the roller pair 230.

[0029] The at least one retraction assembly 214 (represented in block from in FIG. 2) is associated with at least one of the biasing assemblies 212 (and thus the respective one of the roller assemblies 210 connected to the biasing assembly 212). For ease of understanding, FIG. 2 depicts one retraction assembly 214 that is associated with the biasing assembly 212 otherwise connected to the first roller assembly 210a. As described in greater detail below, the retraction assembly 214 is configured to selectively retract the corresponding roller assembly (or roller assemblies) 210a, via interface with the corresponding biasing assembly 212, relative to the glass ribbon 105 (and/or relative to the opposing roller assembly 210 of the roller pair 230) when actuated or prompted by an operator.

[0030] One embodiment of the biasing assembly 212 and the retraction assembly 214 relative to the first roller assembly 210a is shown in greater detail in FIG. 3. The biasing assembly 212 can include a stage 250, a linkage 252 (referenced generally), an arm 254, an optional deadweight or spring 256, and an optional capture element 258. The stage 250 is coupled (directly or indirectly) to the roller assembly 210a, and in particular the shaft 220 (referenced generally). For example, the stage 250 can carry or include a support member 260 that rotatably maintains the shaft 220. The support member 260 can be or include a roller bearing assembly, a drive motor, etc., as understood by one of skill. Regardless, the stage 250 is movably supported relative to the shroud 216 (FIG. 1) or other framework supporting the shroud 216. For example, the stage 250 can be coupled to a bearing member (not shown), such as a low friction bearing (e.g., a linear air slide, rotary air bearing, etc.) that facilitates low friction movement of the stage 250, and thus of the first roller assembly 210a, relative to the glass ribbon 105. In some embodiments, the stage 250 is movable or slidable in a direction transverse to a vertical plane passing through the root 139 (FIG. 1) as indicated by arrow 262. In other embodiments, the stage 250 can be moveable in other directions or paths, including a curved or arc path.

[0031] The linkage 252 is connected to the stage 250 and is configured to dictate or affect a spatial position of the stage 250 along the movement direction 262 relative to the glass ribbon 105. The linkage 252 can assume various forms, and in some embodiments includes a link member 270 and a pivot member 272. The link member 270 is a rigid body that is pivotably connected at opposite ends thereof to the stage 250 and the pivot member 272. For example, an end of the link member 270 is pivotably connected to the pivot member 272 at a connection point 274. The pivot member 272 is pivotably mounted relative to the shroud 216 (FIG. 1) or other framework supporting the shroud 216 such that the pivot member 272 can rotate or pivot about a pivot axis P.

[0032] The arm 254 projects from the pivot member 272 in a direction generally opposite that of the link member 270. In some embodiments, an axis A of the arm 254 is orthogonal to the pivot axis P. Regardless, the arm axis A is vertically off-set from the connection point 274 of the link member 270 to the pivot member 272. For example, the arm axis A and the connection point 274 can be located at opposite sides of the pivot axis P for reasons made clear below.

[0033] The deadweight 256 is mounted to the arm 254 at a location spaced from the pivot member 272. With this construction, the deadweight 256 applies a force (via gravity) on to the arm 254 that in turn generates a moment force at the pivot member 272 about the pivot axis P. A passive bias force is thus applied by gravity through the deadweight 256 and the linkage 252 onto the stage 250, and thus the first roller assembly 210a, biasing the first roller assembly 210a toward the glass ribbon 105 in the production state of FIG. 3. In some embodiments, the biasing assembly 212 is configured to allow for, in the production state, slight displacement of the first roller assembly 210a while in contact with to the glass ribbon 105 due, for example, to variations in a thickness of the glass ribbon 105, variations in the contact surface 222, wearing of the contact surface 222 over time, etc., as is known in the art. As shown in FIG. 4 (in which the retraction assembly 214 and the optional capture element 258 are omitted for ease of understanding), the biasing assembly 212 can be operated or manipulated to retract the first roller assembly 210a relative to the glass ribbon 105 from the production state to a retracted stated by lifting the arm 254. In particular, with the biasing assembly 212 in the production state (drawn in phantom and identified as 212' in FIG. 4), a lifting force LF (upward relative to the orientation of FIG. 4) applied to the arm 254 sufficient to overcome an applied load of the deadweight 256 causes the pivot member 272 to rotate about the pivot axis P, in turn applying a retraction force RF (leftward relative to the orientation of FIG. 4) onto the stage 250 via the link member 270. The first roller assembly 210a moves with movement of the stage 250, and is thus retracted relative to the glass ribbon 105.

[0034] Returning to FIG. 3, where provided, the capture element 258 is coupled to the arm 254, and is spaced from the arm 254 in a direction generally opposite the pivot member 272. The capture element 258 is shaped to define a capture region 280 (referenced generally in FIG. 3). In some embodiments, the capture element 258 is a ring, forming the capture region 280 to have a closed perimeter. In other embodiments, the capture element 258 can have other shapes that may or may not be closed (e.g., the capture element 258 can have an open-ended shape, such as a "U" or "C" shape). A shape and/or dimensions of the capture region 280 can be designed or selected in tandem with a geometry of one or more components of the retraction assembly 214 as described below. The capture element 258 can be coupled to the arm 254 in various fashions, and in some non-limiting embodiments the capture element 258 is provided with or connected to a brace 282 that in turn is configured for mounting to the arm 254. For example, the brace 282 can include a collar 284 adapted to be secured to the arm 254 (e.g., a threaded interface whereby the collar 284 is retro-fitted to a threaded surface of pre-existing arm 254). Other mounting techniques are also acceptable (e.g., mechanical attachment, weld, adhesive, etc.). With these and other embodiments, the capture element 258 can alternatively be provided with other components of the retraction assembly 214 as described above, and assembled or retrofitted to an existing draw apparatus that otherwise includes a biasing assembly comprising the stage 250, the linkage 252, and the arm 254. In other embodiments, the capture element 258 can be more directly secured to the arm 254 with the brace 282 omitted, including the arm 254 and the capture element 258 being provided as a single, homogenous and integral structure.

[0035] In other embodiments the biasing assemblies of the present disclosure can assume a wide variety of other forms as known to those of skill that may or may not be directly implicated by the above descriptions of the biasing assembly 212. Further, the biasing assemblies of the present disclosure can include additional components or mechanisms that operate to effect minor or fine adjustments in a position of the first roller assembly 210a relative to the glass ribbon 105 and/or a pinch force applied to the glass ribbon 105 by the roller pair 230. Regardless, the retraction assembly 214 is generally configured to effect a more overt retraction of the first roller assembly 210a relative to the glass ribbon 105 as described below. In some embodiments, the biasing assembly 212 can have a conventional design and is pre-existing or provided with the glass manufacturing apparatus 100 (FIG. 1); the retraction assembly 214 (and optionally the capture element 258) can be subsequently installed or retro-fitted to the pre-existing biasing assembly 212.

[0036] In some embodiments, the retraction assembly 214 can comprise a drive unit 300 and a line 302. As described in greater detail below, a mechanical coupling between the retraction assembly 214 and the biasing assembly 212 is selectively established via the line 302 and one or more additional, optional components of the retraction assembly 214, such as an engagement element 306. An optional guide device 308 can also be provided to facilitate a useful arrangement of the line 302 relative to the optional capture element 258. In a first state of the retraction assembly 214 reflected by FIG. 3, the retraction assembly 214 is free of mechanical coupling to the biasing assembly 212. In a second state (e.g., FIG. 5 as described below), the retraction assembly 214 is mechanically coupled to the biasing assembly 212 (e.g., the arm 254, the capture element 258, etc.) such that a force generated by the drive unit 300 is transferred via the line 302 to the biasing assembly 212, causing the biasing assembly 212 to transition from the production state of FIG. 3 to the retracted state (FIG. 4).

[0037] The drive unit 300 can assume various forms, and in some embodiments includes a hub or rotor 320 and an actuator 322. The hub 320 is rotatably supported relative to the actuator 322 by a shaft 324, and configured to receive and wind a portion of the line 302 upon rotation about a rotation axis R (e.g., the hub 320 can form a circumferential groove within which the line 302 configured to receive the line 302). The actuator 322 is linked to the hub 320 and is operable to rotate the hub 320 about the rotation axis R. The actuator 322 can assume a wide variety of forms appropriate for applying a force, via an applied torque to the hub 320, onto the line 302 sufficient to lift the arm 254 (e.g., sufficient to overcome a weight force of the deadweight 256 and corresponding torque the deadweight 256 generates relative to the pivot axis P, as well as any frictional forces embodied by the biasing assembly 212), and will vary as a function of the particular design of the biasing assembly 212. For example, the actuator 322 can be or include a servo-motor that is mechanically linked to the hub 320 in a manner such that operation of the servo-motor causes the hub 320 to rotate. Other actuator formats are equally acceptable (e.g., hydraulic-based actuator, pneumatic-based actuator, etc.). Similarly, the drive unit 300 can include one or more additional components. For example, the actuator 322 can be configured to be remotely activated and deactivated via a wired or wireless connection, with the drive unit 300 further including a remote operator interface (e.g., switch, control pad, display screen, etc.) configured or programmed to activate the actuator 322 when prompted by an operator. Further, the drive unit 300 can have other constructions adapted to impart a force (e.g., lifting force) onto the line 302 that may or may not entail rotating a hub to wind the line 302 (e.g., the line 302 can be connected to a vertically moveable drive unit).

[0038] The line 302 is an elongate body that can assume various forms appropriate for transferring a force onto the biasing assembly 212 under the expected operating loads described above. For example, the line 302 exhibits a sufficient tensile or break strength so as to not fail under expected loads. In some embodiments, the line 302 is further configured or selected to exhibit minimal or no elongation under the expected loads or tension. Additionally, the line 302 can be relatively thin, appropriate for winding about the hub 320. With this in mind, the line 302 can, in some embodiments, comprise one or more wires, and may, in some embodiments, comprise a plurality of twisted or braided wires. The line 302 is formed of a material capable of maintaining its structural integrity under expected operating temperatures of the glass manufacturing apparatus 100 (FIG. 1) in a region of the draw apparatus 200 (FIG. 1). For example, the line 302 can be a metal wire, although other materials are also envisioned. With some embodiments in which the line 302 is a wire or similar structure, the line 302 can optionally have a diameter selected to provide requisite strength yet is conducive to manually severing with a cutting tool for reasons described below. For example, in some non-limiting embodiments, the line 302 can be a metal wire having a diameter on the order of 0.8 mm, although other diameters, either greater or lesser, are also acceptable.

[0039] The line 302 can be connected to the drive unit 300 in various fashions. For example, the line 302 can be viewed as terminating at opposing, first and second ends 330, 332 (referenced generally). In some embodiments, a tab 334 projects from the hub 320 as shown, and the first end 330 is secured to the tab 334 (e.g., mechanical fastening, adhesive, weld, etc.). Alternatively, the first end 330 can be attached directly to a surface of the hub 320. Moreover, with alternative embodiments in which the drive unit 300 incorporates a more linear-type actuation mechanism that does not otherwise include a rotatable hub, other forms of attachment of the line 302 to the drive unit can be employed as would be apparent to one of ordinary skill.

[0040] As described in greater detail below, a mechanical coupling is selectively established between the retraction assembly 214 (e.g., the line 302) and the biasing assembly 212 with operation of the drive unit 300. This selective mechanical coupling can be provided in a variety of fashions, and in some embodiments is facilitated by the capture element 258 and the engagement element 306. In general terms, the capture element 258 and the engagement element 306 are designed or configured to be capable of selective contact or engagement, whereby in the first state of FIG. 3, the engagement element 306 is free of contact with the capture element 258; in a second state (described below) of the retraction assembly 214, the engagement element 306 is in physical contact with the capture element 258. [0041] The engagement element 306 is sized and shaped to interface with or engage the capture element 258 when transitioned (e.g., raised) from the first state of the retraction assembly 214 depicted in FIG. 3. In some embodiments, a shape of the engagement element 306 is a sphere or akin to a sphere, although other shapes, such as a cone, pyramid, disc, etc., are also envisioned. Regardless of an exact shape, an outer dimension of the engagement element 306 is selected in accordance with a dimension of the capture region 280 (and/or vice-versa). In particular, and as described in greater detail below, in some non-limiting embodiments at least a major outer dimension of the engagement element 306 is greater than or equal to a minor dimension of the capture region 280 (i.e., minor inner dimension of the capture element 258). With this relationship, the engagement element 306 will contact a surface of the capture element 258 as the engagement element 306 is directed into the capture region 280. The engagement element 306 can be formed of metal or other material capable of maintaining a structural integrity under elevated temperature conditions, and is attached to or formed by the second end 332 of the line 302.

[0042] As generally reflected by FIG. 3, upon final construction of the retraction assembly 214, the drive unit 300 is positioned vertically above the capture element 258, with the line 302 extending or hanging downwardly due to the mass of the engagement element 306 and gravity. As shown, in at least the first state of the retraction assembly 214, the line 302 extends through the capture region 280, locating the engagement element 306 vertically below (and spaced from) the capture element 258. As described below, the drive unit 300 can be installed at various locations along or at the glass manufacturing apparatus 100 (FIG. 1), and thus at different vertical heights or distances relative to the capture element 258. As such, a length of the line 302 can vary as a function of a particular glass manufacturing apparatus installation, and can be selected to provide a vertical gap or margin between the engagement element 306 and the capture element 258 in the first state. Thus, in the first state, the engagement element 306 is free of mechanical coupling to the capture element 258 (and thus to the biasing assembly 212).

[0043] Similarly, the line 302 can be arranged so as to not contact the capture element 258 in the first state of the retraction assembly 214. For example, the optional guide device 308 can be installed vertically between the drive unit 300 and the capture element 258, and is arranged to interface with and align the line 302 relative to the capture region 280. The guide device 308 includes a guide member 350 configured to slidably retain or engage the line 302. For example, the guide member 350 can be or include a hoop, hook, roller, hub, or any other similar structure or mechanism that dictates a spatial position of the line 302 at the point of interface with the line 302, and permits sliding or movement of the line 302 relative thereto (e.g., with operation of the drive unit 300). With this optional construction, then, the drive unit 300 can be located at a multitude of different positions that are horizontally off-set from the capture region 280, with the guide device 308 serving to direct or guide the line 302 from the drive unit 300 into alignment with the capture region 280. Stated otherwise, with the optional embodiment of FIG. 3 in which the drive unit 300 includes the hub 320 from which the line 302 extends, a point of departure 352 (referenced generally) of the line 302 from the hub 320 need not necessarily be vertically aligned with the capture region 280. The guide device 308 can include one or additional components that facilitate assembly or installation to the glass manufacturing apparatus 100 (FIG. 1), such as a bracket 354). In other embodiments, the guide device 308 can be omitted.

[0044] By establishing, in the first state of the retraction assembly 214, a spacing between the line 302 and the capture element 258, and between the engagement element 306 and the capture element 258, the line 302, and thus the retraction assembly 214 (including the drive unit 300), is free of mechanical coupling to the biasing assembly 212. The drive unit 300 can subsequently be operated (e.g., in response to an operator prompt at the actuator 322 or an operator prompt at a remote user interface that is electronically connected to the actuator 322) to transition the retraction assembly 214 to a second state, an example of which is shown in FIG. 5. For example, in transitioning from the first state of FIG. 3 to the second state of FIG. 5, the actuator 322 rotates the hub 320 (counterclockwise relative to the orientation of FIGS. 3 and 5); with this rotation, the line 302 is wound onto the hub 320, in turn raising the engagement element 306 relative to the capture element 258. General alignment of the engagement element 306 with the capture region 280 can be maintained during the lifting operation by an interface between the line 302 and the guide device 308. Operation of the actuator 322 continues until a surface of the engagement element 306 is in contact with a surface of the capture element 304 as in FIG. 5. In the second state of the retraction assembly 214, the retraction assembly 214 (including the drive unit 300) is mechanically coupled to the biasing device 212 via the line 302, the capture element 258, and the engagement element 306.

[0045] In the second state of the retraction assembly 214, further or continued operation of the drive unit 300 imparts a lifting or moment force onto the arm 254 of the biasing assembly 212. More particularly, FIG. 6 illustrates a later stage of operation of the retraction assembly 214 overlaid on the retraction assembly initial stage arrangement of FIG. 3 (with the assemblies 210a, 212, 214 as arranged in the initial stage of FIG. 3 shown in phantom in FIG. 6). The actuator 322 has operated to further rotate the hub 320 in the direction D (i.e., as compared to the arrangement of FIG. 5, the hub 320 has further rotated in the counterclockwise direction to the arrangement of FIG. 6). With this action, the line 302 is further wound onto the hub 320; because the engagement element 306 remains in contact with the capture element 258, a tension force is created in the line 302. This tension force, in turn, is transferred to the arm 254 via engagement between the engagement element 306 and the capture element 258, and connection between the capture element 258 and the arm 254. As the applied force overcomes the load on the biasing assembly 212 (e.g., the deadweight 256), the arm 254 is lifted. Lifting of the arm 254, in turn, transitions the biasing assembly 212 from the production state to the retracted state of FIG. 6, applying the retraction force RF to the stage 250 to retract the first roller assembly 210a away from the glass ribbon 105 (and/or away from the second roller assembly 210b) as described above.

[0046] Returning to FIG. 3, in some embodiments the retraction assembly 214 in the first state does not impact or act upon the biasing assembly 212, and thus does not impact or effect a change in a spatial location of the first roller assembly 210a as otherwise dictated by the production state of the biasing assembly 212. As described above, in some embodiments the biasing assembly 212 is configured to allow or facilitate slight or minor movements of the first roller assembly 210a during normal glass ribbon drawing operations. Under these circumstances, as the stage 250 slides or moves to accommodate or facilitate slight movement of the first roller assembly 210a, the arm 254 will also experience a corresponding level of movement or deflection (e.g., movement of the stage 250 is transferred to the link 270 that in turn causes the pivot member 272 to rotate slightly). The capture element 258 is coupled to the arm 254 as described above, and thus will articulate in tandem with the arm 254 as the first roller assembly 210a experiences slight movements during normal glass ribbon drawing operations. In some embodiments, the retraction assembly 214 is configured to accommodate these slight changes in position of the capture element 258 during normal glass ribbon drawing operations, thereby maintaining a spacing between the line 302 and the capture element 258, and between the engagement element 306 and the capture element 258.

[0047] For example, FIG. 7A is a simplified representation of portions of some embodiments of the retraction assembly 214 in isolation, and illustrates various possible positions of the capture element 258 with movement of the arm 254 (referenced generally) during normal glass ribbon drawing operations as described above. A geometry of the capture region 280 is optionally selected such that the line 302 will not contact the capture element 258 in any of the normal glass ribbon drawing positions of the capture element 258. Further, dimensions of the capture element 258 and the engagement element 306 can be correlated with one another to ensure that a surface of the engagement element 306 contacts a surface of the capture element 258 as the engagement element 306 is lifted or raised as described above. With this in mind, in some embodiments the capture element 258 can be a loop, for example a circular or oval-shaped ring, and the engagement element 306 can be a sphere. With additional reference FIG. 7B (that otherwise illustrates the capture element 258 in isolation), an oval-shaped ring capture element 258 is shown defining a major radius R_eb and a minor radius Rea- The sphere-shaped engagement element 306 defines a radius R_s. Finally, a locus L_arm defining movement of the arm 254 is identified. To better ensure that the line 302 does not inadvertently contact the capture element 258 during normal glass ribbon drawing operations and that the engagement element 306 will contact the capture element 258 when raised, the radius R_s of the sphere-shaped engagement element 306 can be greater than the minor radius R_ea of the oval-shaped ring capture element 258, and the diameter (i.e., two times the radius or 2R_eb) of the oval-shaped ring capture element 258 is greater than the locus L_arm of the arm 254. Other geometries and/or dimensional relationships can alternatively be employed in other embodiments, and can be a function of a selected shape of the capture element 258, a selected shape of the engagement element 306, and/or expected movement path of the arm 254 (or other component of the corresponding biasing assembly to which the capture element 258 is secured). For example, the capture element need not be a closed element, but may, in some embodiments, be an open element, such as a "C" shaped element exhibiting an open (discontinuous) perimeter and a hollow interior.

[0048] Returning to FIGS. 1 and 3, the retraction assembly 214 can be assembled to or provided with the draw apparatus 200 in various manners. In some embodiments, the retraction assembly 214 can be retro-fitted to an existing draw apparatus 200 (or existing glass manufacturing apparatus 100), such as by coupling the capture element 258 to the existing arm 254, and installing the drive unit 300 to an existing framework component of the draw apparatus 200, an existing framework component of the glass manufacturing apparatus 100 apart from the draw apparatus 200, or elsewhere at the glass manufacturing facility in a vicinity of the draw apparatus 200. Where provided, the optional guide device 308 can similarly be installed to an existing framework component. In other embodiments, the draw apparatus 200 is provided to an end user with the retraction assembly 214 previously installed. Regardless, in some embodiments, the drive unit 300, and in particular the actuator 322, can be located away from or outside of draw apparatus shroud 216. This optional installation location can better ensure that the actuator 322 will not be damaged due to heat at or within the shroud 216 during operation of the draw apparatus 200. The first end 330 of the line 302 is then fed through the capture element 258 and secured to the drive unit 300 (e.g., the hub 320). A length of the line 302 can be adjusted to establish a vertical spacing between the engagement element 306 and the capture element 258 as described above.

[0049] While FIG. 1 illustrates one retraction device 214, in other embodiments two or more of the retraction devices 214 can be provided with the draw apparatus 200 (e.g., with respective ones of the retraction devices 214 being associated with a corresponding one of the roller assemblies 210). In yet other embodiments, the retraction devices of the present disclosure can be configured to interface with, or effect selective retraction of, two (or more) of the roller assemblies 210. For example, FIG. 8 illustrates another embodiment of a retraction device 214a in accordance with principles of the present disclosure and in the first state, along with first and second roller pairs 230a, 230b. The first roller pair 230a includes first and second roller assemblies 210a, 210b. A first biasing device 212a as described above is connected to and supports the first roller assembly 210a. The second roller pair 230b also includes first and second roller assemblies 210c, 210d. A second biasing device 212b as described above is connected to and supports the first roller assembly 210c of the second roller pair 212b. The retraction device 214a can be highly akin to the retraction device 214 (FIG. 3), and includes the drive unit 300 and the line 302 as described above. A first capture element 258a is secured to the arm 254 of the first biasing device 212a; similarly, a second capture element 258b is secured to the arm 254 of the second biasing device 212b commensurate with the above descriptions. First and second engagement bodies 306a, 306b are attached to or formed by the line 302. In this regard, a vertical location of the first and second engagement bodies 306a, 306b along the line 302 relative to drive unit 300 is selected such that, in the first state of the retraction assembly 214a, the first engagement element 306a is spaced slightly below the first capture element 258a, and the second engagement element 306b is spaced slightly below the second capture element 258b. With operator-prompted operation of the drive unit 300 (e.g., the actuator 322 rotates the hub 320), the line 302 simultaneously lifts the first engagement element 306a into contact with the first capture element 258a and the second engagement element 306b into contact with the second capture element 258b. With continued or further operation of the drive unit 300, the retraction assembly 214a operates to simultaneously retract the first roller assembly 210a of the first roller pair 320a and the first roller assembly 210c of the second roller pair 320b commensurate with the descriptions above.

[0050] Returning to FIG. 1, some methods of the present disclosure are directed toward controlling operation of the glass manufacturing apparatus 100. The glass ribbon 105 is drawn in a visco-elastic state in a down-draw direction by the draw apparatus 200 operating under normal glass manufacturing production conditions, including the contact surface 222 of the roller assembly (or roller assemblies) 210a with which the retraction assembly 214 is associated being in contact with the glass ribbon 105. Under the normal glass manufacturing conditions, the retraction assembly 214 is free of mechanical coupling to the corresponding biasing assembly 212. The glass ribbon 105 is monitored for possible defects downstream of the roller assembly (or roller assemblies) 210a with which the retraction device 214 is associated. Upon detection of a defect (e.g., crack) in the glass ribbon 105 downstream of the roller assembly 210a with which the retraction device 214 is associated, the roller assembly 210a is retracted so as to remove the contact surface 222 from contact with the glass ribbon 105. In particular, and with additional reference to FIG. 3, the drive unit 300 is actuated to manipulate the line 302 relative to the biasing assembly 212 to mechanically couple the retraction assembly 214 (including the drive unit 300) to the biasing assembly 212. Once mechanically coupled, a force from the drive unit 300 is transferred onto the first roller assembly 210a via the line 302 and the biasing assembly 212 to retract the first roller assembly 210a. With these and other methods of the present disclosure, one or more rollers can quickly be retracted from contact with the glass ribbon as soon as a possible glass ribbon defect is identified.

[0051] Various modifications and variations can be made to the embodiments described herein without departing from the scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modifications and variations come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. An apparatus for drawing a glass ribbon comprising:

a roller assembly comprising a roller;

a biasing assembly configured to selectively change a location of the roller relative to the glass ribbon; and

a retraction assembly transitionable between a first state in which the retraction assembly is free of mechanical coupling to the biasing assembly, and a second state in which the retraction assembly is mechanically coupled to the biasing assembly.

2. The apparatus according to claim 1, wherein the retraction assembly comprises a drive unit and a line connected to and extending therefrom, wherein the line is free of mechanical coupling to the biasing assembly in the first state and is mechanically coupled to the biasing assembly in the second state.

3. The apparatus according to claim 2, wherein the retraction assembly is configured to transition between the first and second states with operation of the drive unit.

4. The apparatus according to claim 2, wherein the biasing assembly comprises a stage coupled to the roller and a linkage connected to the stage.

5. The apparatus according to claim 4, wherein the biasing assembly further comprises an arm projecting from the linkage.

6. The apparatus according to claim 5, wherein the biasing assembly further comprises a capture element coupled to the arm, the capture element defining a capture region.

7. The apparatus according to claim 6, wherein the first state includes the line extending through the capture region.

8. The apparatus according to claim 6, wherein the capture element comprises a loop.

9. The apparatus according to claim 6, wherein the line terminates at a first end opposite the drive unit, and wherein the retraction assembly further comprises an engagement element attached to the first end, the engagement element configured to interface with the capture element in the second state.

10. The apparatus according to claim 9, wherein a shape of the engagement element comprises at least one of a sphere, a cone, and a pyramid.

11. The apparatus according to claim 6, wherein the retraction assembly further comprises a guide device located between the drive unit and the capture element, the guide device interfacing with the line and aligning the line with the capture region.

12. The apparatus according to claim 11, wherein the drive unit is positioned vertically above the capture element and comprises a hub and an actuator operable to rotate the hub, the line including a first end opposite a second end, the second end secured to the hub, and further wherein the retraction assembly comprises an engagement element secured to the first end, and even further wherein transitioning from the first state to the second state includes the actuator rotating the hub to lift the engagement element into contact with the capture element.

13. A glass manufacturing apparatus comprising:

a draw apparatus configured to draw a glass ribbon from a forming apparatus along a draw path extending transverse to a width of the glass ribbon, the draw apparatus comprising:

a first roller assembly including a roller;

a biasing assembly configured to selectively change a location of the roller relative to the glass ribbon; a retraction assembly transitionable between a first state in which the retraction assembly is free of mechanical coupling to the biasing assembly, and a second state in which the retraction assembly is mechanically coupled to the biasing assembly; and

wherein the roller contacts the glass ribbon in the first state of the retraction assembly.

14. The glass manufacturing apparatus according to claim 13, further comprising a shroud defining a chamber within which the glass ribbon travels, and further wherein a drive unit of the retraction assembly is maintained outside of the shroud.

15. The glass manufacturing apparatus according to claim 13, wherein the biasing assembly comprises a stage coupled to the roller, a linkage connected to the stage, an arm projecting from the linkage, and a capture element coupled to the arm, and wherein the retraction assembly comprises a drive unit, a line connected to and extending from the drive unit, and an engagement element attached to the line configured to selectively contact the capture element.

16. The glass manufacturing apparatus according to claim 13, wherein the draw apparatus further comprises a second roller assembly positioned vertically below the first roller assembly and a second roller biasing assembly, and further wherein the first state comprises the retraction assembly free of mechanical coupling to the second roller biasing assembly, and even further wherein the second state comprises the retraction assembly mechanically coupled to the second roller biasing assembly.

17. A method of controlling a glass manufacturing apparatus, the method comprising:

drawing a glass ribbon through a draw apparatus comprising a roller assembly positioned adjacent an edge portion of the glass ribbon, a biasing assembly coupled to the roller assembly and a retraction assembly free of mechanical coupling to the biasing assembly, the step of drawing comprising engaging the glass ribbon with the roller assembly;

monitoring the glass ribbon for defects downstream of the roller assembly;

actuating the retraction assembly upon detection of a defect to mechanically couple the retraction assembly to the biasing assembly; and

transferring a force from the retraction assembly to the roller assembly after the mechanical coupling, thereby disengaging the roller assembly from the glass ribbon.

18. The method of claim 17, wherein the biasing device comprises a stage coupled to the roller assembly, a linkage connected to the stage, an arm coupled to the linkage, and a capture element coupled to the arm, and further wherein the retraction device comprises a drive unit, a line connected to and extending from the drive unit, and an engagement element coupled to the line opposite the drive unit, and even further wherein the step of drawing a glass ribbon includes the line extending through a capture region of the capture element and the engagement element displaced from the capture element.

19. The method of claim 18, wherein the step of actuating the retraction assembly to mechanically couple the retraction assembly to the biasing assembly comprises bringing the engagement element into contact with the capture element.

20. The method of claim 19, wherein the step of transferring a force comprises lifting the arm.